Process of making the chlorinated products of methane



May 15, 1923;

E. H. RIESENFELD PROCESS OF MAKING THE CHLORINATED PRODUCTS OF METHANE Filed Oct. 4

mltoww m16 Inn Patented Mey 15, 1923.

UNITED .STATES a 1,455,508 PATENT omer..

ERNST HERMANN RIESENFELD, OF FREIBURG, GERM'ANY, ASSIGNOR, BY LIESNE ASSIGNMENTS, T THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

PROCESS OF MAKING THE CHLORINATED PRODUCTS Olli' METHANE.

Application led October 4, 1918. Serial No. 256,929.

To all lwhom t may concern:

Be it known that I, ERNST HERMANN Rmsnnmn, a subject of the German Emperor, residing at Freiburg, Germany, have invented certain and useful Improvements in Processes of Making the Chlorinated Products of Methane (for which I have made application in Germany, August 11, 1917); and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

I. The process.

It 'is 'known that the variouschlorinated products of methane or natural gas may be obtained by exposing a mixture of 'chlorine and methane to the light, and it is also known that to' avoid explosions it is advantageous to increase the intensity of the light to which the mixture is exposed by degrees (see German Patent No. 222919'). It is also known that these measures alone do not suffice for the production of the chlorinated products on a commercial scale. Even if the reaction is hastened by the accelerating effect of ordinary indoor temperature it proceeds too 3o slowly for commercial purposes. An ob` vious expedient therefore is to make use of heat as a means for accelerating the re-action. This invention forms the sub]ect matter of y the Austrian Patent No. 63523. But in this patent it is not said how the explosion which, as set forth 'in the German Patent No. 222919 lsometimes occurs suddenly and without any ascertainable reason, and which renders the manufacturing process exceedingly danger- 40 ous, is prevented; Such explosions must occur from time to time, if no special measures are taken to prevent them. They often lead to the destructionoithe entire manufacturng lant, or, at the least, to a breakdown, and) thus considerabl cost of manufacture. vEven t e increasing of the intensity of the li ht by degrees proposed in the German aten't No. 222919 is not a sure means of preventing explosions, because a sudden exposure to light is only one of the numerous causes of explosions, It must, however, be aclm'owledged that by this measure alone a frequent cause of explosion is obviated.

increase the The discovery of another cause of exploslon has now been made and by its being consclously prevented a further increase in the safety of the commercial yplant has been achieved. The newly discovered cause consists in fluctuations of pressure. The prevention of these fluctuations is the object of this invention. It has been found that the pressure waves originating in mixtures of chlorlne and methane are particularly liable to change into explosion waves. It is true that it is not peculiar to themanufacturing process that fluctuations of pressure must arise in it in any case. But aslong as these -are not prevented with forethought they will occasionally arise of themselves in the following instances:

1. By the sudden turning on and off of the gas at the beginning and interruption of the process,

2. By the sudden turning on and off of the light7 in consequence of which the expansion caused by the heat of radiation and by the heat of reaction (or the sudden contraction caused by the opposite process) gives rise to a secondary pressure wave,

8. By the sudden starting and stopping of the cooling in the condensation room. i

An explosion was once observed in connection with this manipulation, which was due to the pressure wave traveling back into the reaction chambers.

The method of obviating fluctuations of pressure consists in providing means for preventing a sudden turning on and ofi' of ga's currents, of the light, and of the cooling devices. These devices are known in themselves. The invention consists in installing them in the manufacturing plant and in making the known method of producing chlorinated products of methane safer and thus cheaper by preventing consciously, and with forethought, sudden fluctuations of pressure.

Il. The pmt.

.The entire plant consists of three units, v1z:

a, the reaction chambers, b, the absorption unit,

c, the condensing unit.

a. The reaction chambers.

The reaction chambers consist of systems i of pipes or chambers through which the tered in any special manner to accomplish the desired result.

The only point of importance is that the gases are completely mixed and that devices are provided (e. g. `regulating cocks) by which the speeds of flow of the chlorine and methane upon entering the mixing chamber may be separately regulated and sudden iiuctuations of pressure prevented. If artificial light, say

a mercury Vapor lamp, is installed in the interior of the reaction chambers, thereaction chambers may consist of opaque material, e. g. earthenware. If the illuminating equi ment is outside the chambers or if daylig t is employed, one or several of the Walls of the chambers must be made of glass or some other material that is transparent to the kind of light used asl an agent for accelerating the reaction. Devices must be installed by which a sudden turning on and oi of the light and a sudden change of 'the temperature of the chamber is prevented.

Furthermore the chambers must be equipped with escape valves suflicient in number and cross section, and these valves must act automatically on a sudden rise of pressure, so as to allow a sufficient quantity of the gases to escape quickly.

i h. The absorption unit.

The absorption of the liquid reaction products methylene chloride, chloroform and carbon tetrachloride, and of the hydrochloric acid which is simultaneously formed, is accomplished by a unit that is designed on lines similar to those of the turill system customary in hydrochloric acid works.

The absorption equipment is 'provided with the usual preliminary cooling devices.

Devices are installed which ensure a gradual turning on said andoff of the cooling Water. Water is supplied in the usual Way to the earthenvvare turill devices, the Water absorbing the hydrochloric acid. As theother products are `insoluble in Water and hydrochloric acid, and they as heavier than these liquids, they settle in the turill devices beneath the hydrous layer. The separation of the hydnous and anhydrous layers may be eected by tapping them ol 4at different heights from the turill devices, or it may be effected in special vessels after the settling of the liquid mixture. The counter current principle will be preferably adopted here, similarly as in the known process for absorbing hydrochloric acid.

c. The emdmmgnmt.

and may be retained in steel bottles, for ex ample. The .final and only residual gas is excess of methane. This may either escape or it may be subjected anew to the manufacturing process.

ln the accompanying drawing there is represented, diagrammatically, an illustrative embodiment of an apparatusin Which the objects of the invention may be attained andin which the reactions may be carried out,

and therein are shown cylinders containing' chlorine and methane, these cylinders being connected by means 0f suitable conduits provided with regulatory devices by means of which the chlorine and methane independently flow into a reaction chamber, which may be of rectangular construction, having a suitable source of light Within, such as an incandescent electric lamp or a mercury vapor lamp, the light source having the current led to it through a rheostat of desired range. The reaction chamber further is equipped With safety valves having a capacity such that When the .pressure of the gases shall exceed a certain definite limit, the excess gases may be quickly removed. The reaction having taken place Within the reaction chamber, the products thereof are led therefrom through an exit conduit to an absorption train Which may consist of a series of Woulfe bottles or turills, each bottle being connected With a reservoir by means of a pipe having a valve therein, and the last of said bottles being connected with a compressor in Which the methane and any uncondensed chlorides of methane are separated. The chlorides, which are condensed, pass from the compressor through a valved pipe to a reservoir, Whereas the methane escapes through a suitable outlet.

In order to provide a desired cooling medium, a liquid Which shall be adapted to 'this purpose is led upon the counter-current principle throu h the Woulfe bottles, entering the bott e nearest the compressor through a pipe provided with a regulatory device. The regulatory devices, or valves, which are used throughout the apparatus are such as will enable the operator to start or to stop the reaction gradually.

III. Process of making metil/yl chlowlde.

If the principal is methyl chloride, the procedure to be observed 1s that the speed of flow of chlorine and methane is such that in the reaction each part of the chlorine reacts with an equal part of methane. Since, if this condition is fulfilled, only small traces of carbon tetrachloride, very little chloroform and only small quantities of methylene chloride are formed, the absorbing equipment required Jfor this process may be small in comparison with the condensing plant. Thus a small are required.

I V. Process of making chloroform.

If the chief product to be prepared is chloroform, three parts of chlorine are allowed to enter into reaction with each part of methane. This renders a larger turill plant and a smaller compression pump nec-y essary.

V. Process of prod/coing carbon tetra chloride.

If the principal product desired is carbon tetrachloride, the speed of flow of the chlorine and methane must be re ulated in such manner that four parts o enter into reaction with each part of methane. Besides carbon tetrachloride, liquid products will then be formed, chiefly chloroform and a small quantity of methyl chloride. In this case the absorption unit willdoe made large and the condensing unit sma VI. Examples.

As an example of the'quantities of reaction products obtained it may be mentioned that, if one part of chlorine enters into reproduct to be obtained" chlorine action with one part of methane, the following quantities result:

Methyl chloride 80% Methylene chloride (CHzClz)- 10% Chloroform 6 0 Carbon tetrachloride (C014) 2% Perchlorethane 2% If about one part of methane enters into reaction with 3 5 parts of chlorine, the quantities obtained are:

Methyl chloride 5% Methylene chloride 7% Chloroform -36% Carbon tetrachloride 42% Perchlorethane 10% I claim.

.-vices which prevent a sudden starting and stopping of the cooling medium.

3. In a system for the production lof chlorinated products of methane from a mixture of chlorine and methane, the improvement which consists in installing devices which prevent a sudden turning on and oil' of the source of actim'c energy.

4. In a system for the production of chlorinated products of methane from a mixture of chlorine and methane, the improvement which consists in installing 'devices which control the flow of gas, the flow of the cooling mediumand the source of actinic energy, whereby-a sudden release and sto page of the said factors are prevented.

n. testimony whereof I aiix my signature, in presence of two witnesses.

ERNST HERMANN RIESENFELD. Witnesses:

JOHANN BAPTIST ZARCK, AUGUST Lrrumr. 

